How Low Can You Go?
How Low Can You Go?
Abstract & Commentary
By Joseph E. Scherger, MD, MPH, Clinical Professor, University of California, San Diego. Dr. Scherger reports no financial relationship to this field of study.
Synopsis: A retrospective analysis of a large international trial of patients with hypertension and coronary artery disease (CAD) showed that lowering diastolic blood pressure (DBP) below 80 mmHg increased the risk of myocardial infarction and all cause death. Patients with a DBP below 70 mmHg had the same adverse outcomes as patients with a DBP over 100 mmHg.
Source: Messerli FH, et al. Dogma disputed: Can aggressively lowering blood pressure in hypertensive patients with coronary artery disease be dangerous? Ann Intern Med. 2006;144:884-893.
Coronary artery perfusion to the heart muscle mainly occurs during diastole. Research has suggested through the years that there may be a J-shaped response to lowering blood pressure in patients with CAD. Benefit occurs up to a point and if the blood pressure is reduced further, adverse events occur. Recent studies have suggested that lowering blood pressure even within normal ranges confers benefit in patients with coronary artery disease.1 Ideal blood pressure is considered around 120/80 or lower and the category of prehypertension has been developed for the risk involved with blood pressures above 130/80 up to 140/90. The focus of recent research has mainly been on the systolic blood pressure (SBP) with is now felt to be the more important of the readings.
A team of investigators from St. Luke's-Roosevelt Hospital in New York looked at the data from an international study of blood pressure lowering in patients with CAD. Named the INVEST trial, and conducted between 1997 and 2003, it compared verapamil with a beta-blocker in 22,576 patients.2 There were 862 study sites in 14 countries. They focused on blood pressure lowering and subsequent mortality, all cause and cardiovascular. The relationship between blood pressure and all cause death and myocardial infarction was J-shaped, particularly for DBP, with a lowest mortality at 119/84. Looking at each 10 mmHg increment, modest increased risk occurred in the group with DBP between 70 and 80 mmHg. The risk rose substantially with DBP below 70, with the same adverse outcomes as patients with DBP above 100.
Commentary
I reported in Internal Medicine Alert in the December 15, 2004 issue3 the study from JAMA which showed that reducing normal blood pressure benefits patients with CAD. Nissen, et al, showed that lowering SBP into the low 120s conferred benefit compared with patients with SBP 130 or above.1 This large multicenter trial (CAMELOT) helped lead to the designation of prehypertension. Little attention was given to DBP levels.
Having graduated from medical school in 1975, I started my career with the teaching that DBP was more important the SBP. Subsequently, multiple studies have shown the important of SBP to the point that is now has superiority of concern in lowering blood pressure. Where is the balance? The fact that coronary artery perfusion occurs mainly during diastole grabs my attention. This study suggests that the current dogma to lower blood pressures as low as possible without causing symptoms is misguided, especially with respect to DBP.
So now we have a balanced consideration with respect to treating hypertension, especially in patients with CAD. Get the SBP down into the low 120s, but do not lower the DBP much below 80. Combining the CAMELOT data with this study from the INVEST trial allows us to fine tune patients' blood pressure therapy. DBP is vitally important, which validates the knowledge from the 1970s.
References:
1. Nissen, SE, et al. JAMA. 2004;292:2217-2226.
2. Pepine CJ, et al. JAMA. 2003;290:2805-2816.
3. Scherger JE. Internal Medicine Alert. 2004;24:178-179.
A retrospective analysis of a large international trial of patients with hypertension and coronary artery disease (CAD) showed that lowering diastolic blood pressure (DBP) below 80 mmHg increased the risk of myocardial infarction and all cause death.Subscribe Now for Access
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